Continue supporting windows 7 with builds

By using an older version of rust to build the artifacts on windows.

Alternatively we could build separate artifacts for windows 7, and
continue using the latest version of rust for later versions of windows
that are more optimized for more recent versions.

Fixes: #1550

.github/workflows/CICD.yml

@@ -111,6 +111,9 @@ jobs:
       uses: dtolnay/rust-toolchain@stable
       with:
         targets: ${{ matrix.job.target }}
+        # On windows, for now build with 1.77.2, so that it works on windows 7.
+        # When we update the MSRV again, we'll need to revisit this, and probably drop support for Win7
+        toolchain: "${{ contains(matrix.job.target, 'windows-') && '1.77.2' || 'stable' }}"
 
     - name: Install cross
       if: matrix.job.use-cross